1. Field of the Invention
This invention relates to methods of fabricating nonvolatile resistive memory elements; in particular, a nonvolatile resistive memory element with a silicon-based switching layer.
2. Description of the Related Art
Nonvolatile memory elements are used in devices requiring persistent data storage, such as digital cameras and digital music players, as well as in computer systems. Electrically-erasable programmable read only memory (EPROM) and NAND flash are nonvolatile memory technologies currently in use. However, as device dimensions shrink, scaling issues pose challenges for traditional nonvolatile memory technology. This has led to the investigation of alternative nonvolatile memory technologies, including resistive switching nonvolatile memory.
Resistive-switching-based nonvolatile memory is formed using memory elements that are bistable, i.e., having two stable states with different resistances. A bistable memory element can be placed in a high resistance state or a low resistance state by application of suitable voltages or currents. Voltage pulses are typically used to switch the bistable memory element from one resistance state to the other. Subsequently, nondestructive read operations can be performed on the memory element to ascertain the value of a data bit stored therein.
As resistive switching memory device sizes are scaled downward in size, it is important to reduce the required currents and voltages necessary to reliably set, reset and/or determine the desired “on” and “off” states of the device, thereby minimizing power consumption of the device, resistive heating of the device, and cross-talk between adjacent devices. However, the high dielectric constant materials currently considered for use as bistable memory elements in such devices, such as HfOx, ZrOx, TaOx, TiOx, and AlOx, can present both performance and manufacturing challenges. For example, these high dielectric constant (high-k”) materials are generally difficult to deposit reliably in the very thin layers desired for resistive switching memory devices. Furthermore, such high-k materials may also not be able to achieve the data retention performance standard expected of nonvolatile memory devices.
In light of the above, there is a need in the art for nonvolatile resistive switching memory devices that are easily manufactured and have robust data retention.